Which expression is equivalent to the given expression?
$\frac{\left(a b^2\right)^3}{b^5}$
A$\frac{a^4}{b}$
B$\frac{a^3}{b}$
C$a^3$
D$a^3 b$
$\frac{\left(a b^2\right)^3}{b^5}$
A$\frac{a^4}{b}$
B$\frac{a^3}{b}$
C$a^3$
D$a^3 b$